I’m still here, just real busy 6

School started the 16th, and I hit the ground running. Once the dust settles, I have a few posts to put up. Please come again.

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6 thoughts on “I’m still here, just real busy

  1. Reply JMG Sep 3,2006 11:03 am

    John:

    Are you aware of Dr. Richard Hake’s work on the difficulty of teaching physics, particularly of replacing incorrect paradigms of how the world works with better ones? In case you are not, see:

    http://www.physics.indiana.edu/~hake/
    http://www.ecologyandsociety.org/vol5/iss2/art28/

    Research, Development, and Change in Undergraduate Biology Education: A Web Guide for Non-Biologists
    http://www.physics.indiana.edu/~redcube/

    He is a consistent participant on POD (Professional & Organization Development Network in Higher Education), archives at:
    http://listserv.nd.edu/cgi-bin/wa?A0=pod&O=D

    His posts always contain citations from the primary literature, being a synthesis, and he is a stickler for emprirical evidence.

    Keep up the good work; our future depends on it.

  2. Reply JMG Sep 3,2006 6:43 pm

    John:

    With regard to the gravity deniers, a fundamental flaw in the argument involving holding a mass at arms length (applying constant force with no work being done in a mechanical sense) but tiring is an apparent ignorance of what is known about muscle function. A quick search of your page below doesn’t indicate that this has been addressed so in case it hasn’t, I’ll tackle it (with the caveat that I am not a physiologist or otherwise expert this) at least to point people in the direction of considering muscle function.

    The process by which muscle fibers generate force is a pulsatile, essentially all on/ all off process for a given fiber, whether or not the entire muscle is changing length or at a steady length. These pulses are milliseconds long and, as I understand it, the fiber is “relaxed” between the pulses. More force is generated by recruiting more muscle fibers, less by fewer. Thus holding a weight at arm’s length requires energy from ATP even when muscle length is constant because muscle fibers are firing on and off to hold it. The complete details of what is happening at the molecular level is still being worked out.

    http://en.wikipedia.org/wiki/Muscle_contraction

    Some creatures have evolved mechanisms to reduce this energy investment. Horses have a stay apparatus that enables them to stand with reduced muscle involvement. If I recall correctly (not a given), horses can lock their leg joints into position.

    http://www.cvm.uiuc.edu/petcolumns/showarticle_pf.cfm?id=119

  3. Reply wheatdogg Sep 6,2006 9:53 pm

    Your explanation about muscle activity agrees with what little I know about physiology, and I believe you are correct about horses’ being able to lock their leg joints. Camels may also be able to do the same, although both animals can lie down on the ground.

    I have heard of Hake’s work indirectly. One of the hardest tasks any science teacher has is to knock out of students’ heads their wrong ideas about all kinds of things scientific. As you can guess, most people are reluctant to give up preconceptions that have so far “worked” for them. Even teenagers, who supposedly are ready to reject anything adult-imposed and adopt anything new and different, fight tooth and nail to maintain their worldviews, no matter how physically wrong.

    Thanks for your words of support. I’m still running at full speed to keep up with the school year, and I’m only three weeks in!

  4. Reply Dave Eaton Sep 11,2006 11:12 am

    JMG-

    Useful background. I alluded obliquely to this in some of the earlier kerfuffle. I think the wiki article is particularly useful, because it underpins that a naive understanding of what goes on in analyzing a physical situation may be hiding what is essential.

    Wheatdogg, the aruments with Wilhelm inspired me to go back to the books and learn a bit more about modern methods in mechanics. I won’t bore with grisly details, but your comment about knocking old ideas out of people’s heads applies. I am trying to grok differential geometrical methods in mechanics, which eschew vectors in favor of differential forms (with an eye to reading an elementary text on general relativity). Whether this particular old dog can be taught this new trick remains to be seen, but it is a fun outlet for my physics envy that your site has rekindled…

  5. Reply wheatdogg Sep 13,2006 11:39 pm

    Dave —

    I envy your free time. I don’t have enough free time to wrap my head around ordinary diff eqs, much less the more esoteric maths you’re trying to grok. I’m afraid my 9th graders will have to wait …

  6. Reply Dave Eaton Sep 15,2006 12:18 am

    Well, I feel really lucky to have the free time. I sure didn’t when I taught just one class at the local CC, and back in school I sure had none. My wife indulges me muttering to myself and scribbling incessantly. Still I have to fit it in after the kids go to bed, so I trade off sleep sometimes. Jose and Saletan’s Classical Dynamics is pretty good, not too esoteric while still using the modern stuff. I have to go slowly, but anything I get out of it is more than I had, so I count it as good.

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